1. Field
The present disclosure relates generally to inspecting objects and, in particular, to performing non-destructive inspection of objects. Still more particularly, the present disclosure relates to a method and apparatus for inspecting objects using ultrasound.
2. Background
In manufacturing aircraft, vehicles, and other structures, inspection of parts used to form these structures is often performed to determine whether the parts will have desired parameters for a desired performance of the part. Non-destructive testing is commonly performed on these parts. Non-destructive testing is used to evaluate properties of a part without altering the ability of the part to be employed in service. Non-destructive testing may include ultrasound testing, eddy current testing, x-ray testing, visual inspections, and other types of testing.
Ultrasound testing is often used to perform inspections on aircraft parts that include or are comprised of composite materials. Ultrasound testing involves transmitting sound waves through a test object. A response to these sound waves is detected. The response is analyzed to determine whether inconsistencies are present in the test object.
Ultrasound testing is commonly performed using a transducer. The transducer is configured to send sound waves into a test object and detect a response to the sound waves. The transducer is typically coupled to a surface of the test object. This coupling involves physical contact between the transducer and the test object.
In many cases, a coupling medium is also employed. For example, water, oil, a water-based gel, or some other liquid may be used. This coupling medium is used to reduce the acoustic impedance between the transducer and the test object.
In some cases, coupling the transducer to the surface of the test object may be more difficult to perform than desired. Difficulty in coupling a transducer to the surface of the test object may occur when the test object has a non-planar surface. In other words, the surface of the test object may have non-planar features. The non-planar feature may be a radius, an edge, a curve, an angle, or other types of non-planar features. When non-planar features are present on the surface of a test object, more difficulty may occur than desired when attempting to ensure that sound enters the test object in a direction that is substantially perpendicular to the surface of the test object. For layered materials such as carbon fiber laminates, perpendicular sound entry is particularly desirable during the inspection process.
Further, the use of a coupling medium may be undesirable with some test objects. For example, the use of a coupling medium may take more time and effort than desired or may be detrimental to the test object.
Therefore, it would be desirable to have a method and apparatus that takes into account at least some of the issues discussed above, as well as other possible issues.